Residential heating, cooling and energy management system

Abstract

A residential HVAC system includes a heat pump having a compressor arranged to heat a domestic hot water vessel and to heat or cool a storage vessel which is connected to a heat exchanger within the residence. Temperature sensors are provided at critical locations throughout the system and current and voltage sensors are coupled to the power lines feeding the residence. A microprocessor controls the operation of the compressor and other components of the heat pump system in response to measured tempertures, in response to the level of energy supplied to the residence and in response to the existence of on- or off-peak time intervals to operate the compressor and/or resistive heating elements to condition the hot water and storage vessels for subsequent use and to control an interior fan to condition the space. Operation of the compressor is controlled during on-peak intervals as a function of the resident's life style as reflected in power usage and requested comfort level.

What I claim is: 
     
       1. A method of operating a residential HVAC system of the type including a first water storage tank, a heat pump system including a compressor, an outdoor heat exchanger, a heat-cool reversing valve, a first refrigerant-to-water heat exchanger having the water side coupled to the storage tank, a water-to-air heat exchanger coupled to the storage tank, means for circulating water through the water-to-air heat exchanger, a duct system for conducting air from the water-to-air heat exchanger to the space within the residence and for returning air from the space to the water-to-air exchanger and a fan for moving air across the water-to-air heat exchanger comprising the steps of selecting a heating or cooling mode in which the system is to be operated and moving the reversing valve to a position appropriate to that selection,   establishing a set point temperature for the space within the residence,   operating the compressor to condition the water in the tank in accordance with the mode selected,   operating a fan at selected intervals of time to circulate air through the duct system and to bring return air to the location of the water-to-air exchanger,   measuring the temperature of the return air immediately upstream of the water-to-air exchanger and comparing that temperature with the set point to determine the difference between the set point and the space temperature, and if the return air temperature differs from the set point temperature by a selected amount, operating the fan and the means for circulating concurrently until the space temperature is within a selected difference band from the set point.   
     
     
       2. A method according to claim 1 which includes, if the space temperature is within the selected difference band from the set point when the fan initially is operated, operating the fan again after a deenergized interval of time and obtaining a new measurement of the space temperature for comparison with the set point. 
     
     
       3. A method according to claim 2 and including providing a second water storage tank for storing domestic hot water, a second refrigerant-to-water heat exchanger having its water side coupled to the second tank and its refrigerant side coupled to the discharge pressure side of the compressor, and a pump for circulating water between the second tank and the second heat exchanger, and   operating the pump when the compressor is operating in either the heating or cooling mode to heat the domestic hot water.   
     
     
       4. A method according to claim 2 and further including measuring the voltage and current supplied to the residence,   calculating the instantaneous power being supplied to the residence,   selecting a maximum power level for desired usage, and   activating an alarm when the calculated power usage exceed the selected level.